The present invention relates to a content addressable memory and a semiconductor device using the same, and is particularly suited to a content addressable memory with low power consumption.
Content addressable memories (CAM) are used in routers and network switches, and required to have larger capacity with increasing network traffic. In virtual networks implemented by the OpenFlow, one OpenFlow controller controls multiple open flow switches in a collective manner. CAMs incorporated in network devices such as OpenFlow switches are required to have large capacity, high-speed throughput, dynamic entry tables, low power consumption, and the like.
Japanese Unexamined Patent Publication No. 2004-295967 (Patent Document 1) discloses a CAM that implements the function of the magnitude comparison and range match comparison between data stored in a storage circuit and search data.
Japanese Unexamined Patent Publication No. Hei 9(1997)-288615 (Patent Document 2) discloses a cache memory device that can improve system efficiency by suppressing access to a main memory in the case of a conflict of or a succession of access to a plurality of memory entries of different tags allocated to the same cache entry.